The patent application requests benefit of the priority on the basis of Japanese Patent Application 2000-300992 applied on Sep. 29, 2000. The contents of this patent application are all incorporated.
(1) Field of the Invention
The present invention relates to an image forming apparatus using liquid developer and more particularly to an image forming apparatus having a liquifying device for liquifying and collecting vapor of a carrier liquid generated in a cabinet.
(2) Description of the Related Art
Image forming apparatuses such as an electrophotographic recording device and an electrostatic recording device using a liquid developer have advantages which cannot be realized by a dry type image forming apparatus and the value thereof has been reviewed recently.
Main advantages of an image forming apparatus using liquid developer against a dry type image forming apparatus are that high image quality can be realized because these image forming apparatuses using a liquid developer can use extremely fine toner particles such as a sub-micron size, and the apparatuses are economical and can realize a texture like printing (for example, offset printing) because sufficient image density can be obtained by a small amount of toner, and energy conservation can be realized because toner can be fixed on a recording form at comparatively low temperature.
On the other hand, a conventional image forming apparatus using a liquid developer includes several essential problems, so that the dry type art has been unrivaled for a long period of time. As one of these problems, a problem concerning a carrier liquid used for a liquid developer may be cited.
Generally, a liquid used as a carrier liquid is a petroleum material and has an odor proper to the petroleum material. To prevent the odor from leaking from the cabinet, various methods are devised so as to collect and remove a carrier liquid.
For example, in Japanese Patent Application Laid-Open 11-249445, a method for press-fitting a cylindrical porous roller to the surface of an electrostatic latent image holding device on which a visible image is formed, thereby absorbs a carrier liquid on the surface of the electrostatic latent image holding device, decompresses the inside of the porous roller by a vacuum pump, thereby removes and collects the carrier liquid absorbed by the porous roller is disclosed.
For example, when the visible image from which the carrier liquid is removed and collected is transferred by feeding heat, the transfer efficiency is improved. However, the carrier liquid on the surface of the latent image holding device cannot be removed completely by the aforementioned removal and collection method, so that the carrier liquid remaining on the surface of the latent image holding device is vaporized by the heat at the time of transfer.
Further, in addition to heating at the time of transfer, there are various heat sources in the image forming apparatus and further, as a carrier liquid generally used, a highly volatile material is used, so that vapor of the carrier liquid is generated in the image forming apparatus during operation.
On the other hand, the image forming apparatus brings a carrier liquid into contact with the surface of the latent image holding device, forms a visible image, transfers the visible image onto a paper, and ejects the paper from the image forming apparatus via the paper ejection port. Therefore, it is difficult to enclose the image forming apparatus completely and vapor of the carrier liquid is diffused outside the image forming apparatus via the ejection port.
In such a problem, to prevent vapor of the carrier liquid from diffusion outside the image forming apparatus, various methods for collecting carrier liquid vapor have been proposed.
For example, there is a method available for bringing vapor of a carrier liquid into contact with an adsorbent such as activated carbon so as to adsorb it. However, the capacity of activated carbon for adsorbing vapor of a carrier liquid is only about 10 to 30% of the weight of activated carbon, so that to adsorb and collect vapor of the carrier liquid generated almost continuously during progress of the image forming process, a large amount of activated carbon must be loaded in the image forming apparatus and the image forming apparatus cannot be miniaturized.
Further, for example, in Japanese Patent Publication 6-58574, a method for sucking vapor of a carrier liquid into a liquifying device, cooling the liquifying device by a Peltier element (thermoelectric element), thereby liquifying the vapor of carrier liquid, and then collecting the carrier liquid in a liquid state is disclosed.
In this method, a power source for functioning the Peltier element must be installed separately. Further, when vapor of a carrier liquid is forcibly cooled by the Peltier element, water vapor coexisting with vapor of the carrier liquid is also liquified and the liquified and collected liquid is a mixture of carrier liquid and water. Namely, water not to be collected originally is also collected, so that problems arise that the container for holding a collected liquid is made larger and when the collected carrier liquid is to be reused for a developer, it must be separated from water once.
As mentioned above, in the conventional method for re-liquifying, collecting, and removing vapor of a vaporized carrier liquid, a forced cooling device such as a piezo-electric element must be installed separately and there are various problems imposed in correspondence to it.
The present invention was developed with the foregoing problems in view and is intended to provide an image forming apparatus using liquid developer for removing vapor of a carrier liquid without using a forced cooling device.
An image forming apparatus using liquid developer of an embodiment of the present invention has a rotary latent image holding device, on the surface of which an electrostatic latent image is formed, a developing device for feeding a liquid developer containing toner particles and a carrier liquid to the electrostatic latent image, thereby forming a visible image on the latent image holding device, a transfer device for transferring the visible image to a transfer material, a cabinet for storing the latent image holding device, developing device, and transfer device, a pipe for sucking gas containing vapor of the carrier liquid vaporized in the cabinet from one end thereof and ejecting it from the other end, and a liquifying device which is connected to the other end of the pipe and has a sectional area 50 times or more of that of the pipe in the perpendicular direction to the moving direction of the vapor ejected from the pipe.
Further, in an image forming apparatus using liquid developer of another embodiment of the present invention having a rotary latent image holding device, on the surface of which an electrostatic latent image is formed, a developing device for feeding a liquid developer containing toner particles and a carrier liquid to the electrostatic latent image, thereby forming a visible image, a transfer device for transferring the visible image to a transfer material, a cabinet for storing the latent image holding device, developing device, and transfer device, and a liquifying device having a suction port for sucking gas containing vapor of the carrier liquid vaporized in the cabinet and an ejection port for ejecting the gas after liquifying the vapor, the liquifying device internally has a plurality of zigzag walls for changing the moving direction of the gas introduced from the suction port and leading the gas to the ejection port.
A carrier vapor processing device of an image forming apparatus using liquid developer of an embodiment of the present invention has a pipe for sucking gas containing vapor of a carrier liquid vaporized in a cabinet of the image forming apparatus using liquid developer from one end thereof and ejecting it from the other end, a liquifying device connected to the other end of the pipe for liquifying vapor of the vaporized carrier liquid, and an ejection port for ejecting the vapor not liquified by the liquifying device.